This invention relates to manually portable gas detecting instruments, and more particularly to a type of instrument having an elongated gas sensing probe mounted thereon to enable a gas sensing element to be moved into relatively inaccessible locations. More specifically, this invention is characterized by including means integral with the housing of such an instrument for storing a flexible probe mounted on it in a protected, nested relationship in which the probe can be readily operated to perform a gas sensing function.
Prior to the invention of the convenient gas detector instrument and associated probe storage means disclosed and claimed herein, the manufacture and use of various types of manually portable instruments having elongated flexible probes coupled thereto was generally well known. Such prior art devices can be broadly categorized into four groups for purposes of brief analysis. First, there are manually portable instruments that are designed to be housed in small cases provided with a handle for carrying the instrument. Ordinarily a coiled, extensible electric cord is plugged into such an instrument to couple it with a sensor assembly that can be extended from the carrying case when the probe is being used to detect a gas or other substance being monitored with the instrument. In such devices, the probe assembly and extensible flexible cord is normally stored within the carrying case when it is not in use, but the probe assembly is not conveniently useable to perform its sensing function when stored within the case. A common modification of the type of instruments within this first general grouping simply provides a hand held instrument with a flexible sensing probe permanently mounted thereon, but does not provide any means for storing the probe in a compact and conveniently portable position relative to the meter, in the manner provided by the present invention. An example of such a prior art meter and associated flexible probe assembly is shown in U.S. Pat. No. Des. 196,875, which issued on Nov. 12, 1963.
A second group or general class of prior art instruments having flexible probes mounted thereon is exemplified by the portable voltage tester illustrated in U.S. Pat. Des. No. 211,088, which issued on May 21, 1968. The voltage tester shown in that patent incorporates within its housing a probe retaining means that secures one probe in operating position on the end of the instrument housing. In association therewith is a second probe coupled to the housing with a resilient flexible electrical conductor. Instruments in this group are similar to those in the first group discussed above in that they do not provide a means for conveniently nesting the flexible portion of the extensible probe assembly in a protected, compact relationship with the instrument housing when the probe is stored. Moreover, as appears to be the case with the voltage tester illustrated in the aforesaid patent, such instruments frequently do not provide means for storing the flexibly mounted probe in a position such that it can be operated to enable the instrument to perform its indicating function while the probe is in its stored position.
A third grouping of such prior art instruments is characterized by providing a portable instrument housing having flexible probe storage means thereon that are operable to partially protect the probe when it is moved to its stored position. In such instruments the protective feature is normally accomplished by moving the probe into a recess or groove in the instrument housing when the probe is rotated to a stored position, in which it is no longer conveniently accessible to afford a sensing function. This third grouping of prior art instruments is, therefore, somewhat similar to a fourth grouping that typically provides a telescopically mounted probe on a portable instrument. This kind of probe is operable to be retracted within the instrument housing when the probe is not in use. Such a telescopically mounted probe on a portable gas detecting instrument is depicted, for example, in U.S. Pat. No. 3,559,049.
All of the aforementioned prior art types of manually portable instruments having flexible probe assemblies associated therewith have certain common disadvantages. Relative to the advantageous features of the present invention, the more outstanding of such disadvantages are that, heretofore, so far as the Applicant knows, none of these devices have provided an integral flexible probe storage means that is operable to retain a flexible sensing probe in a compact, protected relationship to an instrument housing, while at the same time enabling the probe to be conveniently used to perform a sensing function. Moreover, such prior art instrument and probe assemblies typically have not combined a flexible probe function with a hand-held instrument in a manner such that the probe assembly can be compactly stored to enable the instrument to be conveniently fitted into an operator's pocket when not in use.